Telephone system



July ze, 1925. 1,547,489

G. BABCOCKI I TELEPHONE SYSTEM Filed Ja'n. 8- 1921 Patented July` 28, u1925'.-

j,}"junirnn srares enr,

1,547,48e ,nr ossia. l

sannison Bassoon, or nvnnn'rr, WASHINGTON, assionon troA AMERICAN TELE- onnononmnn COMPANY, or nvnnnm, wasnrneron, A conroaATIon' or WASH- moron. Q y

rnnnrnoim SYSTEM.

l Application tiled January 8, 1921.- `Serial No. 435,79@

' My invention relates to telephone systems,

and more particularly to systems involving the use of a call meter or register.

f Measured service as represented by the nickel in 'the slot machine had always been unsatisfactory and is at present particularly so in view of the increasesl in rates.

' which have been placed upon telephone service which require a payment of more than five cents 'per' message. Obviously, 1f the charge for service were'based upon the number of calls and the duration thereoffa fair charge could always be made. My. present- ,25 invention provides a system of very flexible` character which involves no im ediments to perfect service, and which can e employed upon either manual or machine switching systems. The invention is valso applicable to party line systems, and means is rovided to prevent the registration of anca l on the instrument of a party coming in "fon, a busyv party line, or where the' subscriber has an individual line and calls a busy line,"or calls a line which does not answer. This articular means is disclosed and claime yinmy prior Patent, No. 1,138,175, granted May 4, 1 1915. i This ,means which comprises a shunt across the transmitter and the settin coil of the meter permits the subscriber to sten,l but deprives him of the use of theetransmitter .untilthe safety button is released whereupon the message meter-is made operative.,

Fundamentally, the central station apparatus employs means for reversing the polar-1 ity of current supplied to the calling subserihers line after the called party responds. This function is produced by the incorpo'- ration of a pole changing relay in-eaoh answering unit-inthe answering cord of the manual system, or in the selector switch control /feed of the machine switching sys- '15 tem, andis controlled throughfthe` supery 1,186,464, No. 1,189,525, and

'The present invention is lthevform of a cord circuit vised relays or their` equivalents which are under the control "of the called line. l

In a system ofthis character, the meas. urement ot service to private branch .ex` changes or to automatic branch exchange systems is' readily accomplished by adaptin an automatic message meter to each `trunr line. Such meters are common to tors of the private branch exchange or `dials' of the automatic branch exchange system.

The present invention is an improvement all operaupon the systems shown in my prior patents,

namely INo.,v 1,138,174, No. 1,138,1 5, No. No; 1,230,835.

I particularly `concerned withV4 the registration of messages which are limited to three, or tive, or some definite number the central o ce equipment, which .functions -to open the circuit-between subscribers and place a tone signal on the line of the calling party, which will notify the calling subscriber to lower'the switch hook, for the purpose Vof registering the limited calland when this is done, the connection is automatically re-established between the subscribers and another one or more` messages will be recorded according to the length of the connection. This operation is repeated asmany times in a conversation as there are Inultl-4 ples of the timelimit. The arrangement is particularly adapted to automatic and semiautomatic systems where-there is no operator supervision;

i In orderto acquaint those skilled in the art with the manner lof` constructing andy operating my invention, I

shall now describe a specific embodiment of ythe same in con-l nection with the accompanying drawing which. shows a diagrammatic arrangement employing the invention. v

In the diagram shown, I have illustrated two party lines, one of which has connected thereto the vsubscribersy stations A and A and the other of whichv has connected there-l to the subscribers stations B and B.` I

l of minutes'- in duration.. For this pur ose, a time control is added to have also indicated a connecting circuit in ed to be located at the central station to make connection between these lines. The line of the parties A and A comprises the line wires 1 and-2 and the line of the parties B and B comprises the' line wires 3-4. In connection with the following description,

C, which is adapty changing device connected to the answerlingendof the circuit and the time controlled interrupting device92 fory compelling the registration of another rcount upon fthe meter of the calling party upon the completion of a predetermined time interval of connection between the calling and called parties. g l

I have shown a three-strand cord circuit for connecting the two lines, but it is to be understood that a two-strand cord circuit maybe employed as is disclosed in my prior patents, and it is to be further understood that where 'a machine switch is employed at central, the pole changer 10 with the interrupting device 92' is employed in connection with the selector.

The hook switch 8 comprises Jthe usual switch lever 12 of any preferred construction having ahcok at its outer end for reciving the receiver 5 and having the springs is, i4, 15, springs 13 and 16 are connected together and are permanently connected to the line wire 2 through the conductor 18. The contact Y( spring 14ris connected 'through the primary winding of the induction coil 19 and by way of. conductor 20 through the transmitter 6 through-the instrument wire 21. yThis instrumnt wire 21 is adapted to be connected Athrough either the contacts 22---23 vor the ment wires cont-acts 24--25 tothe instrument wire 26 which in turn is connected to the line wire 1. A constant connection betweenthe instru- 21 and 26 exists through the ywinding of the setting coil 27 of the meter 9. The contacts 22- -23 kand 24-25 are adapted to shunt out the coil 27 after said coil has been energized, or uponl polarity which should cause operation of the meter as'distinguished from setting of the same. l

The meter 9 comprises the setting coil 27 and the operating coil 28, both of which are arranged to act upon'the polarizedA armature 31. This armature bears a pawl 32 for operating the counter 33, which is in the nature ofa Veeder counter.

The one terminal of the operating winding of the coil 28 is connected through the wire 30 through the instrument wire 26 and from there to the line wire 1, the other terminal of said coil being connected by wire in two stages through,

C is provided with the polev 16'and 17 of which the two mainy lthe yoccurrence of 34 Ithrough the contactspring 35, which cooperates with a contact spring 36 to prepare a circuit for the 'coil 28 when the setting coil 27 is properlyy energized. The contact spring 36 is connectedby way of thefinstrument wirel 37 to .the hook switch spring 17, contact being made between the springs 16 and 17 when the rece1ver5 is replaced upon Ythe hook.

Thek polarized ringer 7 vis connected directly across the line wires 1 and 2 through the medium of the condenser 38 and instrument wire39. The switch spring. 15 is connected by way of an instrument wire 40 to sliuntout the condenser 38 when the switchhook is raised, so` that the direct current which then tends to iiow through the coils of the'ringer will control the contact 22-23 to insurey that resetting of the meter will not occur unlessproper` polarity of current exists upon the line.` t

The subscribers station is provided with a safety device of the character described and claimed in my prior Patent No'. 1,138,- 17 5 for shunting out i simultaneously -the transmitter 6 and the resetting coil 27 so that a subscriber may listen l1n on a party` line to find out whether the saine isor is not in use, to receive a reply from a called party and thus ascertain ,whether has made response before subjecting himself to a charge for a message. This device comprises the button 41 and the springs-42 i I and 43, the button 41 comprising .a slide which 12, so that the contacts 42 and y43 are automatically closed when the switchI hook lever is depressed. f

The subscribers line 1-2 is providediwith the answering jack `in this case shown as consisting of the springs 45-46 and the ring contact 4f the ring contact in this case controlling the operation of the cut-off relay 48 for disconnecting the 50 when the answering plug is inserted in the jack of the calling line signal relay 4a to efface the line signal party.

The co namely, the tip strand l54, the sleeve strand 55, and a ring strand 56 andi-similar strands 54', 55 and l56 at the ringing end of the and also to permit the subscriberthe correct number v d G comprises three strands,l

lies directly below the switchlever ica cord circuit. The answering and `ringing j ends of the strands are se arated by condensers 57 and 58ywhich, owever, permit the transmission of speech4 therethrough.

The answering end of the cord circuit C is provided with a key 59 for connecting the operators set 60-61 to the cord and is pr'ovided at the ringing end with a key 62 for applying ringing current from a ringing generator 63 to the coiled line.

The system is supplied with current from a common source of current supply which, in'this case, is illustrated at the battery 51 'connections for these relays being cut 'through'the' pole changing switch 10. The

pole changing s\vitch-10-comprises the armaturecontacts 67, 68 and 69 which cooperate -with the stationary contacts 70,. 71, 72 and 7 3. Current is fed to the tip strand of the cord from the battery 51 over the battery Wire 74, contacts 67, 71` over the Wire 76 through the relay 64 andthrough the strand 54. In the same manner, negative battery is normally supplied to the sleeve strand over the battery wire 7 5, contacts 68q-72, wire 77` relay 65 to the strand 55. The supervisory signalwhich is controlled bythe supervisoryrelays 64 and 65 is not shown, asthis is Wellunderstood and need not be illustrated.4

The circuit-of the pole changer relay 66 is controlled at the contacts 78 and 79 of the tip supervisory. relay 64 at the ringing end of the cord circuit. Battery is suppliedthrough the tip relay 64 tothe ringing end of the cord circuit over the battery wire 80. The polarity of the tip strand at .both answering and ringing ends of the cord lcircuit is the same until the pole changingrelay 66 operates to reverse the polarity on the answering end of the cord circuit.

Current is supplied to the sleeve strand of the ripging end of the cord circuit over battery wire 81 and supervisor relay I have provided an interrupting relay 82 which has the armature contacts 83, 84 and 85. These armature contacts 84 and 85 cooperate With back contacts 86 and 87 to interrupt the continuity of the cord circuit whereby conversation between the connected parties is interrupted, and cooperate with the front contacts 88 and 89 to apply a tone signal lo the calling lineto notify the calling subscriber to lower and again raise his switch hook` in order to continue the conversation between the connected parties. 'l`he circuit of the pole changer relay 66 is cut through the contacts 83 and 90 of the interrupting relay 82, so that when the interrupting relay 82 is operated to attract its armature contact, the circuit of the pole changing relay 66 will :be opened and the armature contacts 67, 68 and 69- will be shifted to restore normal polarity of current on the calling line for operating the oper.- ating coil ot the meter at the calling subscribers station. The circuit of the pole changing relay 66 may be traced over the battery wire through the Winding of the relay 66, contacts 83 and 90. wire 91, contacts 78 and 79 of the supervisory relay 64 and hack to battery over the battery wire 80.

The interrupting relay 82 is .quated periodically, namely,j'at the end'of a predetermined period of time after connection between the calling party and the called party is established. For this purpose, I provide the timing device whichcomprises a timing wheel 92 having a raisedcam portion 93 and a Contact controlling linger 94 cooperating with the contacts 95 and 96. The Wheel 92 is adapted to be driven` by means of the friction wheel 97 .and is adapted Vto be returned to its normal position bythe spring 98. held against movement by means of the detent 99 formed on the armature 100 of the starting relay 101. The starting relay 101 is controlled by the pole changer relay contacts 69 and 73 and since the pole changer relay 66 is under the control of the supervisor relay 64' at the ringing end of the cord circuit, it will be apparent that the starting relay' 101 is operated tost'artthe timing wheel 92 only when the called' 4party re-r sponds. 4

The -t'iminr wheel 92 is driven by the friction wheel 97 which friction wheel is driven in turn by the constant speed motor'103,. the circuit of which motor is closed bythe timing relay contacts and 102. The

vshaft of the motor 103 is provided with a flexible coupling 105 and has an armature 106 controlled by the magnet 107 for lapplying the-driving -wheel 97Vto the timing wheel 92. This arrangement merely illustrates a form Aof electrically controlled clutch for connecting together the motor 103 or other suitable source of constant or substantially constant motion withthe timing Wheel 92. The magnet 107 is controlled at the contacts 108 and 109 of the tip supervisor relay 64 on the calling subscribers end of the cord circuit. The circuit for the magnet 107 may be traced over the battery wire 75, contacts 108-109, Wire 110, winding 107 to battery wire 80'.

- If desired, the control of the magnets 101 and 107 may be iuterchanged since the operation of both of these is required to start the timing device.

The supervisory signal on the ringing end of the vcord circuit has not been shown, as this is Well understood in the art.

I believe that the operation of the system will be fully apparent from the foregoing detailed description, but I shall recapitulate briefly the sequence of operations and the relation of the same.

Assume that the calling party A has called central and desires to be connected to the called party B. When the switch hook is down, the contacts 13-14 and 15-16 are opened. so that the talking circuit is interrupted. the meter 9 is in the position shown in the drawing with the contacts 35-36 open and the contacts 24-25 open. The contacts 42 The contacts 164-17 are closed and,

The wheel 92 is 4 lllll 'and43 at. the safety button 41 are closed 'since theslide ofthe `buttonhas been forced down by lowering of theA hook switch lever 12. The calling party removes the receiver 5 from the switch hook opening the contacts 16 and 17 closing contacts 13-14 and 1 5-16. Thepolarity of current is now' such that whatever flow of current there is tothe rin er coils 7 tends to keep the contacts .22

an 23 closed. Thisprotects the setting coil 27 from operation. At th'e same time, the

.contacts 42 and43 are closed until the safety place her talking instruments'60 and 61 in connection with those of the subscriber A.

#Battery is supplied to the line of the calling subscriber over thefollowing circuits: y

From common battery 51, battery lwire 74, -'pole changer contacts 67 and 71, wire 76, tipsupervisor relay 64, tip strand 54,v

line wire 2. to 'the instrument wire 18, contacts 13-and 14 through the primary windingiof the induction coil 19 through the instrument` wire20, transmitter 6, instrument wire 21, contactsi122, '23, instrument wire 26, line wire`1, sleeve strand 55supervisor relay 65, pole changer contacts 72 and 68 back to battery over the battery wire 75.

The operator having ascertained the number of the wanted subscriber inserts the ringing" lug in the `multiple'jack ofthe called su scriber and projects ringing current over the Acalled line'throughl ,the ringer of the called party over the following circuit: I

From the rin er 63, line-wire 3,. instrument wire 18, w1re'39, condenser 38, ringer 7, instrument wire 26 and back over line wire 4 through the ringing generator 63.

If the calling party desires, he may depress the slide 41 to shunt out the transmitter 6 and setting coil 27 of Ahis meter to await the response of thel called party. When the called arty removes the receiver from the switch look and res .onds to the call, the calling party is apprised that the called party is the proper one, then raises the safety slide and button 41 to place his transmitter 6 in operative condition and to permit the settin coil 27 of the meter to 'be opera d to set t e meter.

Bat ery is supplied through the -line of the called party over. the following circuit :r

Battery 51, battery Wire 80, tip relay 64', tip strand 54, line wire 3 through the instrument of the called party B as previousgizes the pole changer relay 66'to reverse the polarity of current on the calling line.

At the same time, the contacts 69 and 73 are closed, these contacts serving to energize the starting relay 101 which lifts the nose 99 of the armature 100 from in front Vof the raised portion 93 and at the same time, closing the contacts 100 and 102 toenergize the driving motor 103. The motor being energized begins to rotate the timing wheel 92 in the direction indicated by the' arrow. It will be understood that thecl'utch magnet 107 Was energized by the closing of contacts 108 and 109` these contacts being under the control of the calling partys supervisor relay 64. The timing ,Wheel92 thereupon begins to operate, the raised portion of the cam 93 holding the contacts 100 and 102 closed until a predetermined time vinterval has elapsed. this time interval being determined byA the time required to rotate` the finger 94 from the-position shown'in the drawings into a position where it closes the contacts 95 and 96. Then these contacts 95 and 96 are closed, a circuit is closed for the interrupting relay 82 las follows:

Battery 5l, battery wire -81, contacts95 and 96, wire 112, interrupting relay 82 and battery wire 74.

The energization of interrupting relay 82 opens the contacts 84, 86 and 85, 87 interrupting the conversation between the parties and applying a tone signal to the calling partys line to apprise hiln of the fact that the period ot' one call has elapsed. To restore' the connection, it is now necessary for the calling party to lower the switch-hook and again raise the same and to open thel contacts 42, 43 whereupon 'the conversation between parties may be resmned. When the interrupting relay 82 is operated, the contacts and 84 are applied to the contacts 89 and 88 respectively, which contacts connect to a suitable source of signaling current. Since clutch magnet 107 is still energized and lfriction wheel 97 still tends to drive the timing wheel 92, the contact.; and 96 will be compelled to close by the finger 94 until the clutch magnet 107 is deenergized. This is under the control of the calling supervisory relay 64 and consequently, it will be necessary for the calling party to open the -circuit in order to permit the return of'the timing wheel 92 to its position :1s-shownA in the drawing, whereupon the contacts 95 and 96 will be again -opened and the interrupting relay 82 le-energized.

.I shall now explain vmore in detail the operation of the pole changer relay in connecmeats@ tion with the meter, Whichoccurs throughout there various stagesrwhich I have above out-lined.

W hen the called party responds, pole changer relay 66 is enengized` as l have pre-y viously indicated, `to send reverse current out over the line of the calling party. Such reversal of current energizes the windings of the ringer bell 7 to open the contacts 22, 23 thereby removing lthe shunt on the magnet col127 which is thereupon energized to attract the adjacent portion of the armature 3l closing contacts 24, 25 to shunt out further pasage of current through the coill27 and to close the contacts 35 and 3.6 to prepare the operating coil 28tor operation of the counter 323. The conversation now procceds to the time when the timing Wheel 92 closes the contacts 95 and 96 whereupon the interrupting relay 82 is energized, this interrupting relay opening the circuit for the pole changer relay 66 at the contacts 83 and 90 whereupon the pole changing relay 66 drops its armatures restoring normal cur- 25 rent to the line. As the'callingl subscriber now depresses the switch hook for the purpose of restoring service, contact is closed etween the springs 16 and .17 at the switch hook, and the operating coil 28 of the meter is energized over the ,following circuit;

Battery 51, battery Wire 74, pole changer contacts 67 and 71, wire 76, supervisor relay 64, tip strand 54, line Wire2, instrument Wire 18, contact 16, contact 17, instrument Wire i 37, contacts 35 and 36, operating coil 28 of the meter, instrument Wire 30, line Wire 1, sleeve strand 55,relay 65, pole changer contact 72 and 68 back to battery over the battery Wire 75. This causes the actuation of the meter and opens the contacts 35, 36 and Q4, 25 so that when the called Darty raises the switch hook to resume the conversation, the setting coil 27 of the relay will again be energized as soon as the interrupting relay 82 is (le-energized. The de-energization of this relay again closes the circuit for the pole changer relay 66 at the contacts 83 and 90, thereby again permitting reverse current to be sent out over the calling line to againset the meter for the next 'charge which Will be made. This operation will be repeated for every multiple of the period of limited service through which the call extends.

llpon the completion of the conversation,l

the parties restore the receivers to theswitch hook, this act at the calling partys station causing the operating coil 28 to be energized again opening the circuit of the instrument and at the same time, adding another count to the message meter.

l do not intend to limit the invention .to the precise details of construction shown and described.

I claim:

l. In a telephone system a calling line having telephone instruments and having a message meter, a called line also having telephone instruments, means for switching said calling line, a called'line also having a telephone set including a switch hook, means for switching said lines into talking connection, said means comprising a switch for setting said message meter upon a response of the called party, and means dependent upon the continuing response of the called party and under the control of the switch hook of the calling jline for operating said meter to register a count upon thpeexpiration of a predetermined period or any multiple of the same during the connection, andmeans under control of the calling party to permit the response of the called party to be heard by the calling party before registration is etlected. y

3. In combination. a calling telephone line having a meter requiring reverse current to set it and direct current to operate it, a plurality of called lines, a connection for supplying direct current tothe calling line to permit the calling line to establish a connection, means under control of the calling party to prevent registration on the meter until the correct party responds, means for reversing current upon the calling line upon response of a connected called line to set the meter. a timing device, and means jointly controlled by the timing device and by the calling line for sending out direct current over the calling line to operate the meter.

4. In a telephone system a calling line having a telephone set and having a message meter, a called line also having a telephone set, means for switching said lines into talking connection, said means comprising mechanism dependent upon the response of the called party, and under the control of the calling line, for operating said meter to register a count upon the expiration cfa predetermined period or any multiple of the same, and for operating the meter to register a count upon restoring the receiver to the switch-hook at the calling partys station and means for connecting the receiver only of the calling party to the called line before each registration.

5. In a telephone system a calling line having a telephone set and having a message polarity vpolarity upon v a telephone set,

`the calling subscriber,

meter operable by reversals of rpolarity on the line, a called line having a telephone set,

a connect-ing circuit comprising a polev changer for changing the polarity of current upon the calling'partys line when the called party responds, and means for interrupting said circuit and restoring the normal polarity upon the line at the end of the predetermined period or any multiple thereof, said means'oomprising a timer for disconnecting the parties and setting the meter and means controlled by the switch hook of the calling party for re-estahlishing the connection and actuating the meter to register or count.

6. In a telephone system a calling line having a telephone set and having a message meter operable by. reversals of polarity on the line, a called liiie having a telephone set, a connecting circuit comprising a pole changer for changing the polarity of current upon the calling party s line when the called vparty responds, a timer at central vstation for periodically interrupting. said circuit' and restoring the normal polarity upon period, and means under the control of the calling part for first listening on the line of thecalle party then restoring the connection and means under the control of the lswitch of the calling party for again placing reversed polarity of current upon the calling line. i

. In combination, a calling line having a telephone set, a called line Ihaving a telephone set, a meter at the telephone set ot the calling subscriber, a connecting circuit4 the lines of the' two sets into said meter being operated by normal polarity of current on the calling line and being set for operation by reverse of current on the calling line, a pole changer switch for supplying normal polarit of current' until the called party respon s and for then supplying reverse the calling line, and timing connecting circuit, sad timing means governing the pole chan er to supply normal polarity to the line or o erating the meter and means for warning 't e calling party of the expiration of each period of time 8. In combination, a calling line having a called line having a telephone set, `a meter at 'the telephone set of a connecting circuit for connecting the lines of the two sets into communication, said meter being operated by normal polarity of current on the calling line,v and being set for operation by reverse polarity ofcurient on the calling line, a pole changerswitch Jfor su plying'noi'mal polarit of current until t e called party respon s and for then supplying reverse polarity upon the callinef line, and timing means for interrupting the connecting cir-r for connecting communication,

means for interrupting the the line at the end of a predetermined der the control ofthe calling party for re` the storing the connection and operating for pole changer'to supply reverse polarity again setting the meter. i v

`9. In combination a calling line having a telephone set and a meter operated by normal polarity of current when the receiver is restored to the switch-hook and being set by reversal of polarity of current on the line when the receiver is switch-hook, a called line having a telephone set and a connect-ing circuit for connecting said lines in telephonie communication, a pole changer switch for supplying normal polarity to the calling line until the called party responds and for then supplying reverse 'polarity to the calling line whereby the meter is set, timing means for interrupting the connecting circuit, said timing means governing the, pole changer to supply normal polarity to the calling linel ofi' the 10. In combination a callingline having i a tele hone set and a meter operated'by norma polarity of current when the receiver is restored to the switch-hook and being set by reversal of polarity of current on the line when the receiver is ofi.` the switch-hook, a called line having a telephone set and-a connecting circuit for connecting said lines in telephonie communication, a pole changer switch for supplying normal polarity to the calling line until the called party responds and for then supplying reverse Apolarity to the calling line whereby the meter is set, timing means for interrupting the connecting circuit, timing means governing the pole changer to supply normal polarity to the calling y line for operating the meter as soon as the receiver of the calling party is replaced on the switch-hook, and means under the control of the switch-hook of the calling party for restoring the connection and operating the pole changer to supply reverse polarity for again setting -the meter of the calling party.

switching imi said

llfi

the connection at the end of a pref means for connecting said lines in telephonie communication, timing means ttor` opening the connection between said lines at. the end of the'predetrmined period, and means under the control of the vcalling partys switch-hook for restoring the c0n` nection and for actuating the lmeter upon each opening of the connection by said tim-` ing means and means for warning the calling party ofthe expiration of each period oftime.

13. In combination a calling line having a telephone set, a called line having al telephone set, a message meter connected to the calling line,.said message meter being controlled by reversals of polarity for operating the meter upon restoration of the receiver to the switch-hook at the calling partys telephone set, means for inter-connecting the lines for telephonie communication, timing means for interrupting said connection until the calling party restores his receiverl to the switch-hook, and means for changing the polarit of current on the calling line when the ine is yinterrupted and for again 'changing the polarity when the connection is restored.

14. A connecting circuit for a telephone line comprising a timing device for opening the connection between the answering end and the calling end of said circuit, said timing means being started upon response of the called party, and being restored upon interruption of the calling line by the calling party to its normal or starting position,

and means controlled by the timing device after the timing device has completedapredetermined movement for reversing the po'- larity of current upon the answering end of the connecting circuit, for operating the meter of a calling party.

15. In a connecting circuit for inter-connecting a calling line and a called line," an interrupting relay for openin the connection between the answering en and the calling end of the connecting circuit,a timing device controlling the operation of said relay, saidgtiming device being started upon the flow of current out over the called line l Without total loss of the'connection between to the telephone instrument of the called party.- a pole changing lswitch for controlling thelpolarity of current supplled tothe telephone instrument of the calling party, said pole changing switch being under the control of said interrupting relaywhereby the pole changer relay will e o erated upon making and breaking of the circuit 'at lthe interrupting relay. and Vmeans under the control of the callin line for re-starting the timing device an for closing the'connection between the answering end and the calling end of the connecting circuit.

16. Iny combination, a timing wheel, a pair of contacts controlled by thev timing wheel, a cord circuit having an interrupting relay controlled by said contacts, a pole changer relay for varying the polarity of current sentto the answering end of the cord circuit, a supervisory relay for the answering end of the cord circuit for controlling lthe restoration-of the 'timing device to starting position, a supervisory relay for the ringing end of the cord circuit for operating the pole changer Vswitch and for starting the-timing -device into operation, said pole ,changer relay being under the control of the interrupting relay.` i

l17. In combinationV a connecting circuit for interconnecting a calling and acalled line, means for supplying current to the. answering end of said connecting circuit, said means including a pole changer relay actuated upon response of the called party, an interrupting relay for interrupting connection of the connecting circuit and of the pole changer relay, a timing device started by operation of the pole changer relay, said device being. adapted to energize'the interrupting relay upon the expiration of a predetermined period of time, and re-setting means for the timing device controlled by ppening of the circuit of the calling party s ine.

18. In combination a'calling partys line having a telephone instrument, a called partys line having a telephone instrument, a messagel meter connected to the calling line, a connecting circuit for interconnecting the lines for telephonie communication, interrupting means for opening said connecting means, a timing means controlling said interrupting means, and means for projecting a distinctive signal over the calling line to advise the calling party that. a predetermined period of time has elapsed during the connection of the calling and called line. 19. In combination a calling line having a telephone set and having a message meterI lconnected incircuit and adapted to be op'- erated upon restoration of the receiver to .the switch-hook, a called line having a telephone .instrument, a connecting circuit for interconnecting the lines, an interrupting device for opening said connecting circuit loss of the connection between the parties,

said interrupting device being time-controlled, and means controlled( by the subscriber in registering a call for closing the open connection of said interrupting device.

21. In' combination. a calling line having telephone instruments meter for said calling line controlled jointly by reversals of polarity on the line and by said switch-hook, a called line having a telehone instrument, a connecting circuit havmg means lor supplying current to the call ing line, a pole changer for the connecting circuit, and a. timing device governing the operation of the pole changer and compelling the lowering of the switch-hook when the connection-consumes more than a predetermined period.

22. In combination a calling line hav-ing telephone instruments and a switch-hook` a l meter for the calling line, said meter being controlled jointly by reversals of polarity on the line and by said switch-hook, a called line having a telephone instrument, a conand a switch-hook, a

necting circuit having means for supplying current to the calling line, a pole changer for said connecting circuitl under the control of the called partys switch-hook, an interrupting device for opening the connecting circuit, und a timing device also controlling said pole changer and governing the interrupting device.

23. In combination, a calling line having telephone instruments and a switch-hook, a meter Jfor said line, controlled jointly by reversals ol' polarityA on the line and by Said switch-hook, means at the central V`station for reversing the polarity of current on the line, and for compelling the lowering of the switch-hook to continue the connection for more than a predetermined period.

ln witness whereof, I hereunto subscribe my name this 29th day of December 1920.

GARRISON BABCOCK. 

